...when it comes to disclosure, talk of unions is a red herring. While they aren't required by the FEC or IRS to disclose donors, a separate piece of federal law, the Labor-Management Reporting and Disclosure Act, requires that unions disclose all sources of income that adds up to more than $5,000, a requirement overseen by the Department of Labor. As a result, unions disclose more than many political groups about their internal operations, and certainly more than than do 501(c)(4) nonprofits like Crossroads GPSCrossroads GPS or 501(c)(6) groups like the Chamber.